In the field of personal lubricants and medicaments applied to mucosal membranes, from time to time attempts have been made to overcome the problem of the perception of cold. When an individual applies personal lubricant or medicament such compositions to internal mucosal membranes, often an individual experiences an uncomfortable, cold feeling due to the difference in temperature between the body and the ambient temperature.
An appreciable number of personal lubricant compositions are known to the art. These compositions range from jellies to liquids to vaginal suppositories and vary from being aqueous to oils to silicone based. The majority of the compositions actually used today are aqueous jellies or aqueous liquids. Almost all personal lubricants known and available for use today are cold to touch, a feeling that can be uncomfortable.
A number of compositions are known to the trade or described in the literature that claim to impart a warming sensation upon application to the skin or mucosa. Some of these compositions use plant extracts which are irritating to the skin and mucous membranes and give a feeling or perception of warmth by virtue of their irritant action. Others claim to enhance blood flow in order to cause tissue warming. Still others are alleged to work on the principle of freezing point depression and are well suited for heating in a microwave or cooling in a refrigerator. There is one cosmetic composition rendered self-heating by inclusion of compound containing a boron-to-boron linkage, which reacts exothermally with water.
One example of a composition known to the trade, Prosensual™, distributed by Lexie Trading, Inc., Fairlaw, N.J., contains plant extracts such as Cinnamon cassia (Cinnamon), Zingiber officinalis (Ginger), Mint, Sandalwood, Orange and Clove, which are all known to be skin irritants. Such a composition has the disadvantage of causing irritation to the mucosa, which can be problematic in relation to the vaginal or oral mucosa as irritation may promote the growth of unwanted bacteria and cause infection.
Another current composition, WET™ Heating Massage Oil, distributed by International, Valencia, Calif., uses Retinyl Palmitate (Vitamin A Palmitate), Prunus amygdalis (Prunes), Amara (Almond), Persica gratissima (Avacado Oil), Macdamia ternifulia Seed Oil, Kakeri Nut Oil, Helianthus annus (hybrid Sunflower), Cannabis sativa (Hemp) Seed Oil and Aloe vera. Most of these ingredients are known irritants that are not suitable for use on mucous membranes.
U.S. Pat. No. 5,895,658, entitled “Delivery of L-Arginine to Cause Tissue Warming, Sustained Release of Nitric Oxide to treat effects of Diabetes, Stimulate Hair Growth and Heal Wounds,” describes a preparation for producing enhanced blood flow in tissues thus causing beneficial effects, such as warming cold tissues of hands and feet.
U.S. Pat. No. 5,513,629 entitled “Microwavable Heat Releasing and Absorbing Compositions and Container, Pliable Gel Comprising Humectant, Freezing Point Depressant, Gel Sealer, Polyacrylamide Absorbent, Corn Starch Binder, Mineral Oil and Plasticizers, Durability, Efficacy” describes compositions that have a high vapor points and are, therefore, suited for heating in a microwave oven or cooling in a freezer and placement in a suitable container or vinyl package, such as a hot-and-cold pack, but not for human consumption or use.
However, none of the foregoing compositions are actually “warm”, or at a relatively higher temperature than the ambient temperature of the product or the surrounding environment.
U.S. Pat. No. 4,110,426, entitled “Method of Treating Skin and Hair with a Self Heated Cosmetic, Organic Boron-Oxygen-Boron Compounds” describes non-aqueous compositions such as shaving creams, that are rendered self-heating by including therein a compound containing at least one boron-oxygen-boron linkage, such as triethoxyboroxine. The boron-containing compound reacts exothermally with water or other protic material to increase temperature. Such compositions are not suitable for vaginal or oral use due to the potential toxicity of boron-containing compounds to the human reproductive system (Fail P A, et al., general, reproductive, developmental, and endocrine toxicity of boronated compounds., Reprod toxicol 12: 1, 1-18, January-February, 1998).
Physical energy forms have been utilized to enhance material transport across a membrane for therapeutic purposes. Such energy forms include electricity, ultrasound and thermal energy (e.g., heat-assisted drug delivery), (reviewed by Sun, in “Skin Absorption Enhancement by Physical Means: Heat, Ultrasound, and Electricity”, Transdermal and Topical Drug Delivery Systems, Interpharm Press, Inc., 1997, pages 327-355). Local heating of a drug delivery system or formulation, as well as the skin or mucosal tissues, not only increases thermodynamic energy of drug molecules and membrane permeability to facilitate drug movement across a barrier membrane, it improves blood circulation in the tissue to expedite drug removal from the local tissue into the systemic circulation. Both processes leads to an enhanced absorption of the drug. Experimental evidence demonstrates that low-level heating (i.e., a tissue temperature of less than about 42° C.) significantly enhances percutaneous drug absorption.
U.S. Pat. No. 5,658,583 describes a heat-generating apparatus for improved dermal permeation of pharmaceuticals. The apparatus includes a thin drug formulation reservoir and a heat-generating chamber of oxidation reaction separated by a non-permeable wall. The drug formulation reservoir houses a predetermined amount of a formulation containing pharmaceutical agents. The heat-generating/temperature-regulating chamber includes a heat-generating medium consisting of carbon, iron, water and/or salt which is activated upon contact with oxygen in the air. However, a complicated heating device such as this is not suitable for use in the vaginal or oral cavity for obvious safety concerns.
Locally applied heat (such as an abdominal heating patch) has also been used to treat dysmenorrhea, or menstrual cramps, with demonstrated efficacy (Akin M D et al., Continuous low-level topical heat in the treatment of dysmenorrhea., Obstet Gynecol 97: 3, 343-9, March, 2001).
U.S. Pat. No. 6,019,782 describes disposable thermal body pads with heat generation via an oxidation reaction intended for relieving menstrual pain when applied onto the abdominal skin. There is currently a commercial product in the U.S. market for dysmenorrhea treatment based on abdominal heating, ThermaCare® Air-Activated Heatwraps, Menstrual Cramp Relief patches manufactured by Procter & Gamble (Cincinnati, Ohio). However, there are no products or description of internal localized heating to treat dysmenorrhea.